The aim of the project proposed here is to accelerate progress in membrane biology by focusing on the key and rate-limiting step in membrane protein structural investigations, which is the crystallization of membrane proteins in a form suitable for high- resolution structural analysis by x-ray crystallography. Several integral membrane proteins have been crystallized by using techniques developed by H. Michel and R. M. Garavito. Recently, the structures of two related photosynthetic reaction center complexes have been solved and the polypeptide chain traced. These major advances clearly identify a way to determine membrane protein structures and thus bring about a much deeper understanding of membrane structure and assembly. The proposal requests support for a workshop to teach membrane protein crystallization methodologies to American investigators. This workshop will be patterned after the two EMBO workshops in Europe, organized by H. Michel and R. M. Garavito, as well as the highly successful First American School in the Crystallization of Membrane Proteins, held in Boulder, Colorado, on December 9-14, 1985. A second workshop would more widely disseminate the new methodologies to membrane biochemists and protein crystallographers and thereby to enlarge the research community trained in these new crystallization techniques. Argonne National Laboratory can provide space and facilities for the workshop and accommodations for most, if not all, of the participants. The central location of Argonne National Laboratory (near Chicago) and the concentration of local expertise in crystallization and determination or structures of membrane proteins, make Argonne an attractive location for the workshop.